Cross-Linked Polyphosphazene Nanospheres Boosting Long-LivedOrganic Room-Temperature Phosphorescence

Long-lived organic room-temperature phosphorescence(RTP) has sparked intense explorations, owing to the outstandingoptical performance and exceptional applications. Because tripletexcitons in organic RTP experience multifarious relaxation processesresulting from their high sensitivity, spin multiplicity, inevitablenonradiative decay, and external quenchers, boosting RTP performanceby the modulated triplet-exciton behavior is challenging. Herein, wereport that cross-linked polyphosphazene nanospheres can effectivelypromote long-lived organic RTP. Through molecular engineering,multiple carbonyl groups (Cxe0c8;O), heteroatoms (N and P), and heavyatoms (Cl) are introduced into the polyphosphazene nanospheres,largely strengthening the spin-orbit coupling constant by recalibratingthe electronic configurations between singlet (Sn) and triplet (Tn)excitons. In order to further suppress nonradiative decay and avoidquenching under ambient conditions, polyphosphazene nanospheres are encapsulated with poly(vinyl alcohol) matrix, thussynchronously prompting phosphorescence lifetime (173 ms longer), phosphorescence efficiency (similar to 12-fold higher), afterglowduration time (more than 20 s), and afterglow absolute luminance (similar to 19-fold higher) as compared with the 2,3,6,7,10,11-hexahydroxytriphenylene precursor. By measuring the emission intensity of the phosphorescence, an effective probe based on thenanospheres is developed for visible, quantitative, and expeditious detection of volatile organic compounds. More significantly, theobtainedfilms show high selectivity and robustness for anisole detection (7.1x10-4mol L-1). This work not only demonstrates away toward boosting the efficiency of RTP materials but also provides a new avenue to apply RTP materials in feasible detectionapplications

Automated summary

This study reports that cross-linked polyphosphazene nanospheres can effectively promote long-lived organic room-temperature phosphorescence (RTP). Through molecular engineering, introducing multiple functional groups greatly enhances the spin-orbit coupling constant, thereby improving the phosphorescence performance. Encapsulating the polyphosphazene nanospheres with a poly(vinyl alcohol) matrix further improves the phosphorescence lifetime, efficiency, afterglow duration time, and absolute luminance, and can be used for detecting volatile organic compounds.